对立统一是一个哲学概念，最早的提出者是古希腊哲学家赫拉克利特。阿那克西曼德认为所有元素皆为相互对立。现代哲学中的对立统一是一个辩证法上的概念，有时可见于形上学或科学领域。

• "Heraclitus on Change and Unity of Opposites"

The unity of opposites was first suggested by Heraclitus (ca. 535–475 BC), a pre-Socratic Greek philosopher.

Philosophers had for some time been contemplating the notion of opposites. Anaximander posited that every element was an opposite, or connected to an opposite (water is cold, fire is hot). Thus, the material world was composed by some indefinite, boundless apeiron from which arose the elements (earth, air, fire, water) and pairs of opposites (hot/cold, wet/dry). There was, according to Anaximander, a continual war of opposites. Anaximenes of Miletus, a student and successor of Anaximander, replaced this indefinite, boundless arche with air, a known element with neutral properties. According to Anaximenes, there was not so much a war of opposites, as a continuum of change. Heraclitus, however, did not accept the milesian monism and replaced their underlying material arche with a single, divine law of the universe, which he called Logos. The universe of Heraclitus is in constant change, but also remaining the same. That is to say, an object moves from point A to point B, thus creating a change, but the underlying law remains the same. Thus, a unity of opposites is present in the universe as difference and sameness. This is a rather broad example though. For a more detailed example we may turn to an aphorism of Heraclitus: